Film-Enclosed Formed Bath Experience Products and Method of Manufacture

ABSTRACT

A film-enclosed bath article and a method of manufacturing the same is disclosed. The method includes providing a formed bath article enclosing the formed bath article in a water-soluble film. The formed bath article is capable of producing a gas upon contacting a liquid. The water-soluble film has a thickness between approximately 10 μm and approximately 28 μm. The method further includes heating the water-soluble film to a temperature of at least approximately 300° F. to cause the water-soluble film to shrink around the formed bath article.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Application No. 63/045,071, filed Jun. 27, 2020. The priority application is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to packaging and, more particularly, to packaging and manufacture of bath experience products.

BACKGROUND

Bath experience products such as a bath bomb or shower steamer are mixtures (e.g., a compressed mixture) of dry ingredients which effervesce when wet. Bath bombs can be used to add essential oils, bubbles, fragrance, fizz, and color to bath water or a wet shower environment. The base ingredients can be a weak acid and a carbonate or bicarbonate base. These are unreactive when dry, but react vigorously when dissolved in water to produce gas over a period of several minutes.

Bath experience products are typically packaged and shipped within a film product or package (e.g., polypropylene, a rigid or loose cellulosic material, a plastic clam-shell package, and/or a multi-chambered cuboid box) that must be opened in order to remove the bath experience product prior to use by the consumer. Over time, these products may lose moisture prior to use (e.g., during transit and while they are on display at retail locations), and as such, they may become brittle and/or cracked and prone to damage, revealing undesirable visible imperfections upon the consumer removing the product from the package. Further, during transit to the consumer, these products may be subjected to stress and other damage that may create visible flaws. Such flaws may negatively impact the consumer's bath experience. Conversely, consumers oftentimes find more involved packaging solutions such as individual blister packaging to be undesirable due to potentially increased costs and the perception of excess waste materials.

SUMMARY

One aspect of the present disclosure provides a method of making a film-enclosed bath article that includes providing a formed bath article enclosing the formed bath article in a water-soluble film. The formed bath article is capable of producing a gas upon contacting a liquid. The water-soluble film has a thickness in a range of approximately 10 μm to approximately 28 μm. The method further includes heating the water-soluble film to a temperature of at least approximately 300° F. (148° C.) to cause the water-soluble film to shrink around the formed bath article. In some embodiments, the formed bath article may include an aroma ingredient.

In some examples, a physical movement disturbance may be applied to the film-enclosed formed bath article during the heating step. In some of these examples, the physical movement disturbance may be in the form of a turbulent fluid air flow applied to or around the film-enclosed formed bath article. In some examples, the physical movement disturbance may be in the form of agitation applied to the film-enclosed formed bath article.

In some approaches, at least one perforation may be formed that extends through the thickness of the water-soluble film prior to or during heating, preferably prior to heating. In some of these examples, the at least one perforation extending through the thickness of the water-soluble film may be formed prior to enclosing the formed bath article therein. In some examples, the film-enclosed formed bath article may be disposed in a heating chamber which is enclosed or partially enclosed, e.g. a tunnel. Further, in some approaches, the at least one perforation extending through the thickness of the water-soluble film may be formed via at least one member disposed within the heating chamber.

In some forms, the water-soluble film may be in the form of a melt-blown film material. In some examples, the water-soluble film may be in the form of an oriented film. The formed bath article may be formed in at least one of a spherical shape, a hemispherical shape, or a non-rectilinear shape. In embodiments, the formed bath article can have a major dimension, e.g. a maximum diameter, in a range of approximately 1 inch (2.54 cm) and approximately 3 inches (7.62 cm). In some embodiments, the film may be in the form of a water-soluble polyvinyl alcohol resin which is a polyvinyl alcohol homopolymer, polyvinyl alcohol copolymer, or a combination thereof.

In accordance with another aspect of the present disclosure, a film-enclosed bath article is provided that includes a formed bath article including an aroma ingredient and a water-soluble film. The formed bath article has a non puck-shaped body and is capable of producing a gas upon contacting a liquid. The water-soluble film has a thickness in a range of approximately 10 μm to approximately 28 μm and is configured to enclose the formed bath article therein and shrink around the formed bath article upon being heated to a temperature of at least approximately 300° F. (148° C.).

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter that is regarded as the present invention, it is believed that the invention will be more fully understood from the following description taken in conjunction with the accompanying drawings. Some of the figures may have been simplified by the omission of selected elements for the purpose of more clearly showing other elements. Such omissions of elements in some figures are not necessarily indicative of the presence or absence of particular elements in any of the exemplary embodiments, except as may be explicitly delineated in the corresponding written description. None of the drawings are necessarily to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention.

FIG. 1 is a perspective view of one embodiment of a film-enclosed formed bath article constructed in accordance with various embodiments of the present disclosure;

FIG. 2 is a schematic view of an example formed bath article of FIG. 1 prior to placement in an example water-soluble film in accordance with various embodiments of the present disclosure;

FIG. 3 is a schematic view of the example formed bath article of FIGS. 1 and 2 upon placement and sealing of the water-soluble film in accordance with various embodiments of the present disclosure;

FIG. 4 is a schematic view of the example formed bath article of FIGS. 1 and 2 disposed in a second example water-soluble film arrangement in accordance with various embodiments of the present disclosure;

FIG. 5 is a front side elevation schematic view of an example heating chamber for use in manufacturing the film-enclosed formed bath article of FIGS. 1-4 in accordance with various embodiments of the present disclosure;

FIG. 6 is a right side elevation schematic of the example heating chamber of FIG. 5 in accordance with various embodiments of the present disclosure; and

FIG. 7 illustrates a perspective view of an alternative film-enclosed bath article arrangement in accordance with various embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure generally concerns the manufacture and configuration of a film-enclosed bath article which may be used to enhance a consumer's bath experience. In some examples, the film-enclosed bath article may include an effervescing and/or aromatic component contained within that is released when the object is placed in a water-filled bath tub (or other water-filled receptacle). Advantageously, the film-enclosed bath article described herein is manufactured in a way that it needn't be removed from its packaging, and can be placed into the water-filled bath tub to generate the desired effervescing and/or aromatic effect. More specifically, a water-soluble film is provided that encloses the formed bath article to protect the formed bath article. Due to the water solubility of the film, both the formed bath article and the film may be placed in the water-filled tub to begin the effervescing and aromatic effects upon dissolution of the film and contact of the formed body with water.

Additionally, the film-enclosed formed bath articles described herein are manufactured in a way that generates a smooth, clean appearance having minimal flaws and other visual disturbances. More specifically, during a heat shrinking process in which the water-soluble film shrinks to the shape of the formed bath article, heat is applied to the film-enclosed formed bath article in a substantially even manner to all sides of the article to reduce obstructions, bends, and/or other visual imperfections in the film.

Turning to the drawings, a film-enclosed formed bath article 100 is provided that includes a formed bath article 110 (e.g., a bath bomb) and a water-soluble film 120. As previously noted, in some examples, the formed bath article 110 is a mixture, e.g. a compressed mixture, of dry ingredients which effervesce when wet. In other examples, the formed bath article 110 may be formed via wet granulation, dry molding, and/or wet molding. Other examples are possible. The formed bath article 110 can be used to add essential oils, bubbles, fragrance, fizz, color, and/or words to bath water or, in some examples, a wet shower environment. In some examples, the formed bath article 110 is constructed from a weak acid and a carbonate or bicarbonate base. Such materials are unreactive when dry, but react vigorously when dissolved in water to produce gas over extended periods of time (e.g., for several minutes). This is an acid-base reaction that involves conversion of the weak acid and carbonic acid salt to the corresponding acid salt and carbon dioxide, e.g. citric acid and sodium bicarbonate to sodium citrate and carbon dioxide.

In some approaches, the weak acid can be a carboxylic acid, e.g. selected from monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids. The weak acid can be one or more of citric acid, fumaric acid, and tartaric acid, for example. In some cases, the acid can be present as an acid salt, e.g. potassium bitartrate, which dissociates in water to suitable acid and salt. In some approaches, anhydrous acids can be used. The carbonate can be selected from alkali metal carbonates and alkali metal bicarbonates, for example. The carbonate can be one or more or more of calcium carbonate, magnesium carbonate, sodium carbonate, and sodium bicarbonate, for example.

As previously noted, such formed bath article 110 compositions can contain scented ingredients to provide a desired fragrance to the environment. The fragrance can consist of or include one or more essential oils. For example, the one or more essential oils can be Armois, Benzoin, Cardamom, Chamomile blue, Grapefruit, Hydrangia, Jasmin, Labdunum, Lavender, Lemon, Lemon myrtle, Lemongrass, Litsea Cubeba, Neroli, Orange 50 fold, Patchouli, Peppermint, Rose otto, Rosemary, Sweet violet, Tarragon, Tonka, Vanilla, and Ylang. Other examples are possible. Such compositions can contain dyes or pigments, preferably water-soluble dyes, to release a desired color, for example, to the bathwater. Such compositions can also contain a lathering agent such as, for example, sodium lauryl sulfate, to assist in creation of longer-lasting bubble foam. Other surfactants can include lauryl ether sulphates, ethylene oxide/propylene oxide alkyl phenol condensates, polyglycol ethers of fatty alcohols, fatty acid ethylene oxide condensates, polyglycol ethers of alkyl phenols, and fatty alcohol ethoxylates. The compositions can include binders, lubricants and carriers, such as polyethylene glycol (PEG) sorbitol and maltodextrin, for example. The composition can include a vegetable oil, e.g. selected from one or more of almond oil, argan oil, castor oil, coconut oil, grape seed oil, jojoba oil, and olive oil. Solid carriers can be used, e.g. water soluble components in powdered form. Solid carrier materials can be powders selected from one or more of salt, sugar, sorbitol, cream of tartar, magnesium carbonate, magnesium sulfate, and a clay. Clays can be selected from one or more of kaolin, Fuller's Earth and bentonite clays, for example. In one aspect, the solid carrier material may be any combination of salt, sugar, sorbitol, cream of tartar, and mixtures thereof. The composition can include one or more decorative items, e.g. glitter, paper such as rice paper, sequins, dried or fresh flowers, herbs, vegetables, parts thereof or mixtures thereof. Other examples are possible.

In embodiments, the carbonate or bicarbonate can be present in an amount of about 40 wt % to about 95 wt. % based on the total weight of the composition, e.g. 45-95 wt. %, or 50-95 wt. %, or 50-90 wt. %, or 55-90 wt. %, or 60-85 wt. %, or 60-80 wt. %, or 60-75 wt. %. The acid component can be present in an amount of 5 to 55 wt. % of the composition, e.g. 10-50 wt. %, or 20-40 wt. %, or 25-35 wt. %, or 5-30 wt. %. In one embodiment, the composition include sodium bicarbonate in an amount of 40 to 75 wt % based on and citric acid in an amount of 24 to 40 wt %. When present, the color agent can be present in an amount in a range of about 0.001 to 5 wt. % based on the weight of the composition, e.g. 0.001 to 4 wt. %. Further, when present, the fragrance can be present in an amount in a range of about 0.001 to 10 wt % based on the total weight of the composition, e.g. 0.001 to 8 wt. %, or 0.1 to 4 wt. %. When present, the surfactant can be present in an amount in a range of 0.1 to 8 wt %, for example 0.5 to 5 wt %. The vegetable oil or other binder can be present in an amount in a range of about 0.001 to 12 wt. %, e.g. 0.1 to 10 wt. %, or 0.1 to 5 wt. %.

The formed bath article 110 may take any number of shapes. For example, the formed bath article 110 may have a generally spherical, semi-spherical, non-rectilinear, rectilinear, and/or any other shape or type of shape. Further, in some examples, the formed bath article 110 may be in the form other geometric shapes or other patterns such as stars, faces, and the like. In some examples, the formed bath article 110 may have a major dimension (e.g., a length, diameter, width, height, etc.) in a range of approximately 1 inch (2.54 cm) and approximately 3 inches (7.62 cm)″. Other examples are possible.

The water-soluble film 120 may be in the form of a sheet dimensioned to retain the formed bath article 110. The water-soluble film 120 may be in the form of a melt-blown film material, an oriented film, and/or any other type of suitable film. In some examples, the thickness of the water-soluble films 120 may be in a range of approximately (e.g., ±10%) 10-28 μm, or 12-26 μm, or 14-24 μm, or in a range of 16-22 μm.

To be considered a water-soluble film according to the present disclosure, the film, at a thickness of about 28 microns dissolves in 300 seconds or less in water at a temperature of 23

in accordance with MonoSol Test Method MSTM-205, optionally less than 200 seconds, or less than 100 second, so less than 909 seconds, or less than 80 seconds, or about 70 seconds. Optionally, the film can be characterized by a disintegration time in 23° C. water according to MonoSol Test Method MSTM-205 for a 28 micron film of less than 30 seconds, or less than 10 seconds, or less than 8 seconds, or less than 6 seconds, or about 4 seconds.

The water-soluble film may include one or more polyvinyl alcohol (PVOH) resins disclosed herein to make up the PVOH resin content of the film, and can include a PVOH copolymer resin.

Polyvinyl alcohol is a synthetic resin typically prepared by the alcoholysis, usually termed hydrolysis or saponification, of polyvinyl acetate. Fully hydrolyzed PVOH, where virtually all the acetate groups have been converted to alcohol groups, is a strongly hydrogen-bonded, highly crystalline polymer which dissolves only in hot water—greater than about 140° F. (about 60

). If a sufficient number of acetate groups are allowed to remain after the hydrolysis of polyvinyl acetate, that is, the PVOH polymer is partially hydrolyzed, then the polymer is more weakly hydrogen-bonded, less crystalline, and is generally soluble in cold water—less than about 50° F. (about 10

). As such, the partially hydrolyzed polymer is a vinyl alcohol-vinyl acetate copolymer that is a PVOH copolymer, but is commonly referred to as homopolymer PVOH. Polyvinyl alcohol is usually prepared by the hydrolysis of a polyvinyl ester, most commonly polyvinyl acetate. Rather than from polyvinyl acetate, the polyvinyl alcohol may be made by hydrolyzing other polyvinyl esters such as polyvinyl formate, propionate, butyrate, hexoate, benzoate, or the like.

The film may be produced by any process, for example by extrusion and blowing or by casting. The film may be unoriented, monoaxially oriented or biaxially oriented. If the film has multiple layers and the layers in the film are oriented, they can optionally have the same orientation. In one type of embodiment, the film is melt-blown and oriented, optionally bioaxially oriented, or optionally monoaxially oriented.

The film can be a melt-blown, partially saponified (partially hydrolyzed) polyvinyl acetate, commonly referred to as polyvinyl alcohol. Suitable films, related formulations, and methods of making are described in U.S. Pat. Nos. 3,365,413, 3,607,812, and 4,119,604, 8,438,819, and the patents cited therein, which are incorporated herein by reference.

The viscosity of a PVOH polymer resin is determined by measuring a freshly made solution using a Brookfield LV type viscometer with UL adapter as described in British Standard EN ISO 15023-2:2006 Annex E Brookfield Test method. It is international practice to state the viscosity of 4% aqueous polyvinyl alcohol solutions at 20° C. All viscosities specified herein in Centipoise (cP) should be understood to refer to the viscosity of 4% aqueous polyvinyl alcohol solution at 20° C., unless specified otherwise. The polyvinyl alcohol resin (individual, or average of mixtures) can be characterized by a viscosity in a range of about 4 to about 45 cP, or about 4 to about 18 cP, or about 4 to about 13 cP, or about 4 to about 12 cP, for example about 4 cP, about 6 cP, about 8 cP, about 10 cP, about 12 cP, or about 20 cP. In one type of embodiment, the viscosity is in a range of 4 to 40 cP.

The major portion of the film is a polyvinyl alcohol resin, or mixture thereof. For example, the polyvinyl alcohol resin portion of the film can be at least 50 wt. %, or in a range of about 50 wt. % to about 95 wt. %, or about 60 wt. % to about 90 wt. %, or about 70 wt. % to about 85 wt. %, or about 75 wt. % to about 85 wt. %, or about 80 wt. % to about 80 wt. %. In one type of embodiment, the polyvinyl alcohol resin portion of the film is present in an amount of 60 wt. % to about 90 wt. %.

The water-soluble film can include water-soluble polymers in addition to the polyvinyl alcohol resin described herein. The additional water-soluble polymers can include, but are not limited to, another vinyl alcohol-vinyl acetate copolymer, often referred to as a PVOH homopolymer. They can include a partially or fully hydrolyzed PVOH copolymer that includes an anionic monomer unit, a vinyl alcohol monomer unit, and optionally a vinyl acetate monomer unit. In various embodiments, the anionic monomer can be one or more of vinyl acetic acid, alkyl acrylates, maleic acid, monoalkyl maleate, dialkyl maleate, monomethyl maleate, dimethyl maleate, maleic anhydride, fumaric acid, monoalkyl fumarate, dialkyl fumarate, monomethyl fumarate, dimethyl fumarate, fumaric anhydride, itaconic acid, monomethyl itaconate, dimethyl itaconate, itaconic anhydride, citraconic acid, monoalkyl citraconate, dialkyl citraconate, citraconic anhydride, mesaconic acid, monoalkyl mesaconate, dialkyl mesaconate, mesaconic anhydride, glutaconic acid, monoalkyl glutaconate, dialkyl glutaconate, glutaconic anhydride, vinyl sulfonic acid, alkyl sulfonic acid, ethylene sulfonic acid, 2-acrylamido-1-methyl propane sulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, 2-methylacrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl acrylate, alkali metal salts of the foregoing (e.g., sodium, potassium, or other alkali metal salts), esters of the foregoing (e.g., methyl, ethyl, or other C1-C4 or C6 alkyl esters), and combinations of the foregoing (e.g., multiple types of anionic monomers or equivalent forms of the same anionic monomer). For example, the anionic monomer can include one or more of monomethyl maleate and alkali metal salts thereof (e.g. sodium salts). The additional polymer can also be selected from polyacrylates, water-soluble acrylate copolymers, polyvinyl pyrrolidone, polyethyleneimine, pullulan, water-soluble natural polymers including, but not limited to, guar gum, gum Acacia, xanthan gum, carrageenan, and starch, water-soluble polymer modified starches, copolymers of the forgoing and combinations of any of the foregoing. Yet other water-soluble polymers can include polyalkylene oxides, polyacrylamides, polyacrylic acids and salts thereof, celluloses, cellulose ethers, cellulose esters, cellulose amides, polyvinyl acetates, polycarboxylic acids and salts thereof, polyaminoacids, polyamides, gelatines, methylcelluloses, carboxymethylcelluloses and salts thereof, dextrins, ethylcelluloses, hydroxyethyl celluloses, hydroxypropyl methylcelluloses, maltodextrins, polymethacrylates, and combinations of any of the foregoing. Such water-soluble polymers, whether PVOH or otherwise, are commercially available from a variety of sources.

The total PVOH resin content of the film can have a degree of hydrolysis (D.H. or DH) of at least 60%, 70%, 80%, 84%, or 85% and at most about 70%, or 75%, or 80%, or 99.7%, or 98%, or 96%, for example in a range of about 60% to 99%, or 60% to 75%, or 84% to about 90%, or 85% to 88%, or 86.5%, or in a range of 85% to 99.7%, about 88% to 98%, or 90% to 96%, for example, 91%, 92%, 93%, 94%, 95%, or 96%. E.g., in one type of embodiment the degree of hydrolysis is in a range of 70% to 99%. As used herein, the degree of hydrolysis is expressed as a mole percentage of vinyl acetate units converted to vinyl alcohol units.

If present at all, water can constitute less than 0.5% of the weight of the extrudable polyvinyl alcohol-based composition, although it is possible to blow-extrude certain compositions containing up to about 1.0% by weight of volatile material such as water. The water content of the final film, after pickup of atmospheric moisture or by intentional conditioning, can be in a range of 2 wt. % to about 10 wt. %, for example.

The water-soluble film including the resin disclosed herein can contain other auxiliary agents and processing agents, such as, but not limited to, plasticizers, plasticizer compatibilizers, surfactants, lubricants, release agents, fillers, extenders, cross-linking agents, antiblocking agents, antioxidants, detackifying agents, nanoparticles such as layered silicate-type nanoclays (e.g., sodium montmorillonite), bleaching agents (e.g., sodium metabisulfite, sodium bisulfite or others), fragrances, and other functional ingredients, in amounts suitable for their intended purposes. Embodiments including plasticizers are preferred. In embodiments, the water-soluble film includes a surfactant, an antioxidant, a perfume, an anti-block agent, or combinations thereof. The amount of auxiliary agents can be, for example, up to about 50 wt. %, 20 wt. %, 15 wt. %, 10 wt. %, 5 wt. %, 4 wt. % and/or at least 0.01 wt. %, 0.1 wt. %, 1 wt. %, or 5 wt. %, individually or collectively.

A plasticizer is a liquid, solid, or semi-solid that is added to a material (usually a resin or elastomer) making that material softer, more flexible (by decreasing the glass-transition temperature of the polymer), and easier to process. A polymer can alternatively be internally plasticized by chemically modifying the polymer or monomer. The water soluble film described herein can comprise one or more plasticizers. In addition or in the alternative, a polymer can be externally plasticized by the addition of a suitable plasticizing agent. When included, the plasticizer can be included at a concentration of about 10 to about 40 parts per 100 parts of total polyvinyl alcohol resin, for example, or about 6 wt. % to about 20 wt. % of the film, optionally about 8 wt. % to about 16 wt. %, or about 10 wt. % to about 12 wt. %. In one type of embodiment, the film will include one or more polyol plasticizers at a concentration in a range of 5 wt. % to 35 wt. %.

The plasticizer can include, but is not limited to, glycerol, diglycerin, sorbitol, ethylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycols up to 400 MW, hexylene glycol, neopentyl glycol, trimethylolpropane, polyether polyols, polyether diol, polyether triol, xylitol, 2-methyl-1,3-propanediol (MPDiol®), ethanolamines, glycerol propylene oxide polymers (such as, for example, Voranol™ available from The Dow Chemical Company), and a mixture thereof. A combination of glycerine and sorbitol is contemplated. Plasticizers can also include one or more compounds such as monophenyl ethers of polyoxyethylene containing from 2 to about 7 ethylene oxide units per molecule. These ethers are available commercially as mixtures (PYCAL); those mixtures having an average ethylene oxide content of about 4 units per molecule are contemplated. Other polyvinyl alcohol plasticizers may also be used, and optionally in conjunction with the PYCAL type of compound just described. Included in this class are ethylene oxide derivatives of furfuralcohol containing about 3 to 12 moles of ethylene oxide per molecule, ethoxylated derivatives of urea (e.g. NOPCO 68-5) and of tetrahydrofurfuryl alcohol, tributyl phosphate, tributoxyethyl phosphate, dimethylformamide, ethanol foramide, trimethylol propane, and so on.

Suitable lubricants for use in the water-soluble films described herein can include, but are not limited to, fatty acids and their salts, fatty alcohols, fatty esters, fatty amines, fatty amine acetates and fatty amides. Preferred lubricants/release agents are fatty acids, fatty acid salts, and fatty amine acetates. In one type of embodiment, the amount of lubricant/release agent in the water-soluble film is in a range of about 0.02 wt. % to about 1.5 wt. %, optionally about 0.1 wt. % to about 1 wt. %.

Antioxidants in small amounts optionally can be used in the compositions to minimize thermal degradation. The compounds can have a measure of water solubility and can be reducing agents. A list of compounds in this category includes butylated hydroxyanisole, butylated hydroxytoluene, sodium benzoate, calcium stearate, lactose, and salts of copper, nickel, cobalt and tin. From 0.01 to 2.0% of said compounds may be used, based on the total weight of the film.

An anti-block agent (e.g. SiO2 and/or stearic acid)) can be present in the film in an amount of at least 0.1 parts per one hundred parts polyvinyl alcohol resin (PHR), or at least 0.5 PHR, or at least 1 PHR, or in a range of about 0.1 to 5.0 PHR, or about 0.1 to about 3.0 PHR, or about 0.4 to 1.0 PHR, or about 0.5 to about 0.9 PHR, or about 0.5 to about 2 PHR, or about 0.5 to about 1.5 PHR, or 0.1 to 1.2 PHR, or 0.1 to 2.7 PHR, for example 0.5 PHR, 0.6 PHR, 0.7 PHR, 0.8 PHR, or 0.9 PHR. A suitable median particle size for the anti-block agent includes a median size in a range of about 3 or about 4 microns to about 11 microns, or about 4 to about 8 microns, or about 5 to about 6 microns, for example 5, 6, 7, 8, or 9 microns.

The film can be characterized by having a tensile strength (according to ASTM D 882) in a range of about 30 to about 60 MPa, for example in a range of about 40 MPa to about 60 MPa in the machine direction and optionally or in combination about 30 MPa to about 40 MPa in the transverse direction.

The film can be characterized by having a tensile strain at break (according to ASTM D 882) in a range of about 90% to about 300%, for example in a range of about 90% to about 150% in the machine direction and optionally or in combination about 200% to about 300% in the transverse direction.

The film can be characterized by having a Yield (according to ASTM D4321) in a range of about 20 m²/kg to about 50 m²/kg, for example in a range of about 25 m²/kg to about 40 m²/kg.

In one aspect, the polyvinyl alcohol film formulation to be prepared by blow-extrusion will melt at a temperature in a range of about 375° F. to about 425° F., or about 190° C. to about 220° C.

In one aspect, the film can be transparent or substantially transparent. For example, the water-soluble film, at a thickness in a range of 10 micron to 28 micron, has a measured opacity of about 37.0% or less, or 30% or less, or 20% or less, as determined by an X-RITE SP60 Series Sphere Spectrophotometer X-64 colorimeter, or substantial equivalent.

In one embodiment, the water-soluble film 120 may be a PVOH film having the following characteristics:

(a) about 60 wt. % to about 90 wt. % polyvinyl alcohol homopolymer resin having a viscosity in a range of about 4 to about 40 cP, and about 70% to about 99% degree of hydrolysis;

(b) about 0 wt. % to about 35 wt. % one or more polyol plasticizers; and

(c) about 2 wt. % to about 10 wt. % water.

The tendency for PVOH films to absorb moisture caused a prejudice against its use in the present applications. However, the present inventors found that instead of providing moisture to the effervescent bath article and degrading its properties, the film acts as a moisture buffer to better preserve the bath article and delay its transition to a more brittle, friable form.

The ability of PVOH to become crosslinked, and thus insoluble, by reaction with acids such as citric acid, succinic acid, and tartaric acid, caused a prejudice against use of polyvinyl alcohol-based films for wrapping citric acid-containing bath products, such as those claimed herein. However, the present inventors found that the polyvinyl alcohol films retained their solubility despite long-term contact with such bath products.

In some examples, to enclose the formed bath article 110 within the water-soluble film 120, the water-soluble film 120 is first folded over to form a first side edge 122 and first and second sections. A lower edge 126 may then be formed via any number of suitable approaches such as, for example, a hand-held L-bar sealer. Next, a second side edge 124 may be formed via the L-bar sealer (or any other suitable approach). Accordingly, the water-soluble film 120 may form a pouch in which the formed bath article 110 may be disposed (FIGS. 2 and 3 ). As illustrated in FIG. 3 , the L-bar sealer (or any other suitable approach) may form and seal an upper edge 128, thus enclosing the formed bath article 110 within the water-soluble film. In some examples, the L-bar sealer may be capable of heating to a temperature sufficient to not only seal the edges of the water-soluble film 120, but also to sever the film, and thus cut the excess water-soluble film 120 from the sheet. In other approaches, an automated and/or semi-automated machine may seal the water-soluble film 120 to enclose the formed bath article 110.

In embodiments, the sealed article is a vertical form, filled, and sealed article. The vertical form, fill, and seal (VFFS) process is a conventional automated process. VFFS includes an apparatus such as an assembly machine that wraps a single piece of the film 120 around a vertically oriented feed tube. The machine heat seals or otherwise secures the opposing edges of the film 120 together to create the side seal and form a hollow tube of film. Subsequently, the machine heat seals or otherwise creates the bottom seal, thereby defining a container portion with an open top where the top seal will later be formed. The machine introduces a specified amount of product, e.g. a spherical bath bomb, or optionally a plurality of items, into the container portion through the open top end. Once the container includes the desired amount of product, the machine advances the film 120 to another heat sealing device, for example, to create the top seal. Finally, the machine advances the film to a cutter that cuts the film immediately above the top seal to provide a filled package. Optionally, the film can be simultaneously sealed and cut.

During operation, the assembly machine advances the film 120 from a roll to form the package. Accordingly, the film 120 must be able to readily advance through the machine and not adhere to the machine assembly or be so brittle as to break during processing.

With reference to FIG. 4 , an alternative approach is illustrated in which the water-soluble film 220 is sealed at eight edges to more closely surround the exterior of the formed bath article 220. Accordingly, in such examples, the heat-shrinking process (described below) may result in fewer “dog ears” (i.e., corners or visual disturbances).

With reference to FIGS. 5 and 6 , one example heating apparatus 130 is provided for heat-shrinking the water-soluble film 120 around the formed bath article 110. The heating apparatus 130 may include an interior volume 130 a, a conveyor or platform 134, any number of heating elements 136, and any number of agitating members 138. The conveyor or platform 130 may be movable or stationary and accommodates and supports the film-enclosed formed bath article 100 thereon. In some examples and as illustrated, the heating apparatus 130 may be horizontally oriented, but any number of suitable arrangements and/or orientations are possible.

The film-enclosed formed bath article 100 is placed within the heating apparatus 130 and can be moved within the interior volume 130 a thereof (e.g., from a first end 132 a to a second end 132 b thereof). The heating element or elements 136 may be positioned at any location within or near the interior volume 130 a of the apparatus (e.g., at or near an upper surface, at or near a side surface, at or near a lower surface, etc.), and may heat the interior volume 130 a to suitable temperatures. More specifically, in some examples, the heating element or elements 136 may heat the interior volume 130 a, and thus the water-soluble film 120, to a temperature of at least approximately 300° F. (148° C.), or in a range of about 300° F. to about 450° F. (about 148° C. to about 230° C.), or about 300° F. to about 400° F. (about 148° C. to about 200° C.), for example about 148° C., about 150° C., 160° C., 180° C., 190° C., 200° C., or 220° C. The temperature to which the film is heated can optionally be below the temperature at which the film melts. This temperature will cause the water-soluble film 120 to shrink around the formed bath article 110.

In some examples, while heating the water-soluble film 120 and the formed bath article 110, the apparatus 130 may apply any number of physical movement disturbances to the film-enclosed formed bath article 100 to assist uniformly shrinking the water-soluble film 120. More specifically, in some examples, the heating element or elements 136 may generate and apply turbulent fluid air flow (e.g., vortex heating) to the film-enclosed formed bath article 100. In some examples, the apparatus 130 may include additional turbulent flow generators such as fans (not illustrated) that are separate from the heating element or elements 136.

Alternatively or additionally, while heating the water-soluble film 120 and the formed bath article 110, the apparatus may cause the film-enclosed formed bath article 100 to move, roll, shift, and/or rotate. More specifically, as the film-enclosed formed bath article 100 moves from the first side 132 a to the second side 132 b of the apparatus 130, the agitating members 138 may cause the film-enclosed formed bath article 100 to move, roll, shift, and/or otherwise rotate to cause the water-soluble film 120 to shrink more evenly, e.g. by exposure to sufficiently high temperatures around the article in a more uniform fashion, in contrast to spot heating. In other examples, the conveyor or platform 130 may vibrate, undulate, and/or generate any other type of movement. In yet other examples, a user may simply push or urge the film-enclosed formed bath article 100 along the conveyor or platform 134 to generate the desired agitation. Other examples are possible.

By applying a physical movement disturbance to the film-enclosed formed bath article 100, the water-soluble film 120 may evenly and uniformly shrink, thus reducing the amount of excess water-soluble film not properly surrounding the formed bath article 110, e.g. gathering at an end, side, or other locations around the body. This can especially be a concern with non-rectilinear bodies, including spherical bodies.

In some examples, the film-enclosed formed bath article 100 may include any number of perforations 129 extending through the thickness of the water-soluble film 120. In some approaches, the perforations 129 may be applied to the water-soluble film 120 prior to placing the formed bath article 110 within the water-soluble film 120. In other approaches, the perforations 129 may be applied to the water-soluble film 120 after placing the formed bath article 110 within the water-soluble film 120 but before the heating step. In yet other examples, the perforations 129 may be applied to the water-soluble film 120 during the heating step. More specifically, the apparatus 130 may include any number of perforating members (not illustrated) capable of forming the perforations 129 through the thickness of the water-soluble film 120 while the film-enclosed formed bath article 100 is within the interior volume 130 a thereof. In some approaches, the agitating members 138 may include sharpened portions, pins, and the like, that may be capable of forming the perforations 129 as the film-enclosed formed bath article 100 passes through the apparatus 130. Other examples are possible.

The perforations 129 may provide a number of advantages to the film-enclosed formed bath article 100. For example, the perforations 129 may assist in causing the water-soluble film 120 to uniformly shrink during heating. The perforations 129 may allow for air trapped between the film 120 and bath article 110 to more evenly escape as the film 120 is shrunk. Additionally, the perforations 129 may assist in off-gassing of CO2 in the formed bath article 110. Put differently, the water-soluble film 120 does not act as a moisture barrier, and as such, air may enter the water-soluble film 120 which may assist with retaining the original configuration of the formed bath product 110. Further, the perforations 129 may allow small amounts of odor to pass through the water-soluble film 120 such that a user may determine the smell of the formed bath article 110 before purchase or use.

It will be appreciated that while an apparatus 130 is described to heat the film-enclosed formed bath article 100, in some examples, the film-enclosed formed bath article 100 may be manually packaged by manually sealing the water-soluble 120 and using a hand-held heating device (e.g., a heat gun) to shrink the water-soluble film 120. In such examples, a manufacturer may manually move the film-enclosed formed bath article 100 and create turbulent fluid flow by hand. Further, the manufacturer may manually create perforations 129 through the thickness of the water-soluble film 120. Other examples are possible.

With reference to FIG. 7 , an alternative film-enclosed formed bath article 300 is provided that includes a belly band region 327 formed in the water-soluble film 320. In some environments, generally spherical formed bath products 310 may result in imperfections when heating and shrinking the water-soluble film 320. In these examples, instead of completely encompassing the formed bath product 310, a portion (e.g. approximately in a range of 1% to 50%, or 5% to 20%) of the body surface area that would otherwise be covered with the water-soluble film 320 is left open and defines one or more voids 327 a. Such a configuration provides most of the benefit of enclosing the formed bath product 310 in the water-soluble film 320 while creating a more aesthetically pleasing water-soluble film free of dog-ears and/or nipple shapes. In such an embodiment, e.g. a sphere, the article 310 can be wrapped with a band of film 320 that is a closed rectangle, and then shrunk to form the belly band 327, or two sides of the closed band of unshrunken film 320 can be tapered so that they better conform to the surface of the spherical bath product 310 upon heat shrinking to form the belly band 327. In these types of examples, the belly band region 327 can also be manually cut to remove excess water-soluble film 320 material.

From the foregoing, it can be seen that the present disclosure advantageously provides an improved configuration and method of manufacturing a film-enclosed bath article. By using the water-soluble films described herein, the film-enclosed formed bath article needn't be removed from its packaging prior to use. As such, any imperfections in the formed bath article are not perceived prior to use, thus enhancing the user's bath experience, and the product may remain protected during transit. For example, fractures throughout the body of the bath article would not be evident. As another example, any product dust from the body of the article would be contained within the water-soluble film, and would never be evident to the end user. The film-wrapped article also may convey superior quality when on display. Further, because of the water-solubility of the film, there is no excess waste upon using the product. Additionally, it is appreciated that any number of additional shapes and/or profiles of formed bath articles may be used while still evenly and uniformly shrinking that otherwise would be too difficult to manufacture using conventional methods.

While the present disclosure has been described with respect to certain embodiments, it will be understood that variations may be made thereto that are still within the scope of the appended claims. 

1. A method of making a film-enclosed bath article, the method comprising: providing a formed bath article, the formed bath article being capable of producing a gas upon contacting a liquid; enclosing the formed bath article in a water-soluble film having a thickness between approximately 10 μm and approximately 28 μm; and heating the water-soluble film to a temperature of at least approximately 148° C. to cause the water-soluble film to shrink around the formed bath article.
 2. The method of claim 1, further comprising the step of applying a physical movement disturbance to the film-enclosed formed bath article during the heating.
 3. The method of claim 2, wherein the physical movement disturbance comprises providing a turbulent fluid flow to the film-enclosed formed bath article.
 4. The method of claim 2, wherein the physical movement disturbance comprises agitating the film-enclosed formed bath article.
 5. The method of claim 1, further comprising forming at least one perforation extending through the thickness of the water-soluble film prior to heating.
 6. The method of claim 5, wherein the at least one perforation extending through the thickness of the water-soluble film is formed prior to enclosing the formed bath article therein.
 7. The method of claim 5, further comprising the step of disposing the film-enclosed formed bath article in a heating chamber.
 8. The method of claim 7, wherein the at least one perforation extending through the thickness of the water-soluble film is formed via at least one member disposed within the heating chamber.
 9. The method of claim 1, wherein the formed bath article comprises an aroma ingredient.
 10. The method of claim 1, wherein the water-soluble film comprises a melt-blown film material.
 11. The method of claim 1, wherein the water-soluble film comprises an oriented film.
 12. The method of claim 1, wherein the formed bath article is formed in at least one of a spherical shape, a non-rectilinear shape, or a hemispherical shape.
 13. The method of claim 12, wherein the formed bath article includes a major dimension between approximately 1″ and approximately 3″.
 14. The method of claim 1, wherein the film comprises a water-soluble polyvinyl alcohol resin which is a polyvinyl alcohol homopolymer, polyvinyl alcohol copolymer, or a combination thereof.
 15. A film-enclosed bath article, comprising: a formed bath article, the formed bath article having a non puck-shaped body and being capable of producing a gas upon contacting a liquid; a water-soluble film having a thickness between approximately 10 μm and approximately 28 μm, the water-soluble film configured to enclose the formed bath article therein and shrink around the formed bath article upon being heated to a temperature of at least approximately 300° F.
 16. The film-enclosed bath article of claim 15, wherein the formed bath article is formed in at least one of a spherical shape, a non-rectilinear shape, or a hemispherical shape.
 17. The film-enclosed bath article of claim 15, further comprising at least one perforation extending through the thickness of the water-soluble film.
 18. The film-enclosed bath article of claim 15, wherein the water-soluble film comprises a melt-blown film material.
 19. The film-enclosed bath article of claim 15, wherein the water-soluble film comprises an oriented film.
 20. The film-enclosed bath article of claim 15, wherein the formed bath article includes a dimension between approximately 1″ and approximately 3″.
 21. The film-enclosed bath article of claim 15, wherein the formed bath article comprises an aroma ingredient.
 22. The film-enclosed bath article of claim 15, wherein the film comprises a water-soluble polyvinyl alcohol resin which is a polyvinyl alcohol homopolymer, polyvinyl alcohol copolymer, or a combination thereof.
 23. The film-enclosed bath article of claim 15, comprising the formed bath article and the water-soluble film being in a heat-shrunk form around the formed bath article. 